MINNEAPOLIS (WCCO) — We’ve all been at the dentist with the round X-ray machine shoved against our jaw, biting down on plastic pieces of film with a lead apron on our chests. Now researchers have identified a possible connection between a brain tumor and dental X-rays. So are we being X-rayed too much?

At ADT Dental in Minneapolis, first- and third-graders Kelly and Adrian Contreras both got their teeth cleaned, and neither of them had an X-ray.

“We don’t do it as often as we used to,” said their mother Laura.

It’s no accident. Dr. Adele Della Torre said she’s made a conscious effort to cut down on radiation exposure for her patients.

“Of course we all worry about it, we want to keep it as low as possible,” said Della Torre. “When I was a kid, it was every time you went to the dentist.”

Now the equipment has gotten more sensitive, requiring lower doses of radiation. Della Torre spent the money to outfit her office with a digital X-ray system.

The manufacturer told her it uses 90 percent of the radiation compared to the older X-ray machines, and about half the radiation of the current film X-ray machines.

“You place [a digital sensor] in the mouth instead of the film, it’s very sensitive to the radiation, and you see the image on the screen,” she said.

Researchers in the journal “Cancer” found that people who got a dental X-ray at least once a year were up to two times more likely to develop meningioma, the most common type of brain tumor found in Americans.

The research was based on a questionnaire, and people’s memory of their dental X-ray history is certainly questionable. The study also doesn’t prove that X-rays cause tumors, rather that there’s a link between the two.

Still, considering the low dose of radiation in a dental X-ray, the information has the dental community taking notice, and looking at how often people should get their teeth X-rayed.

If you have healthy teeth and you’re being X-rayed every year, it’s probably too much, according to the American Dental Association’s current guidelines.

“Right now the recommendation is every two years, if you take care of your teeth,” said Della Torre. “Then there are people who hardly ever have decay, we get X-rays every three years, at least in our office.”

The radiation from modern X-ray machines is so low, the lead apron isn’t really necessary. But the American Dental Association still recommends a lead thyroid collar.

“It goes around and protects your thyroid. The thyroid gland is more susceptible to the radiation exposure,” said Della Torre.

On the scale measuring exposure to radiation, a set of dental bitewing X-rays is very low, close to zero. In fact, about the same exposure you get during a two-hour airline flight.

“If you break a bone, that’s a lot more radiation. Dental X-rays are really minimal compared to medical X-rays,” said Della Torre.

By comparison, a chest CT scan is equivalent to the average background radiation we’re exposed to from the sun and earth in a year.